#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int64 INF = 1LL << 60;

int main()
{
  int N, M, K, S, T;
  scanf("%d %d %d %d %d", &N, &M, &K, &S, &T);
  vector< pair< int, int > > ev[200000];
  for(int i = 0; i < M; i++) {
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    ev[a].emplace_back(c, b);
  }
  ev[0].emplace_back(S, -1);
  ev[N - 1].emplace_back(T, -1);
  for(int i = 0; i < N; i++) {
    sort(begin(ev[i]), end(ev[i]));
  }

  auto sweep = [&](vector< int64 > &dp, int idx)
  {
    for(int i = 1; i < dp.size(); i++) {
      dp[i] = min(dp[i], dp[i - 1] + ev[idx][i].first - ev[idx][i - 1].first);
    }
    for(int i = (int) dp.size() - 2; i >= 0; i--) {
      dp[i] = min(dp[i], dp[i + 1] + ev[idx][i + 1].first - ev[idx][i].first);
    }
  };

  vector< int64 > dp(ev[0].size(), INF);
  dp[lower_bound(begin(ev[0]), end(ev[0]), make_pair(S, -1)) - begin(ev[0])] = 0;
  sweep(dp, 0);


  for(int i = 1; i < N; i++) {
    vector< int64 > dp2(ev[i].size(), INF);
    for(int j = 0; j < ev[i].size(); j++) {
      auto &p = ev[i][j];
      if(p.second == -1) continue;
      int q = lower_bound(begin(ev[i - 1]), end(ev[i - 1]), make_pair(p.second, -1)) - begin(ev[i - 1]);

      if(q < ev[i - 1].size()) {
        dp2[j] = min(dp2[j], dp[q] + ev[i - 1][q].first - p.second);
      }
      --q;
      if(0 <= q && q < ev[i - 1].size()) {
        dp2[j] = min(dp2[j], dp[q] + p.second - ev[i - 1][q].first);
      }
    }
    sweep(dp2, i);
    dp.swap(dp2);
  }

  auto ret = dp[lower_bound(begin(ev[N - 1]), end(ev[N - 1]), make_pair(T, -1)) - begin(ev[N - 1])];
  if(ret >= INF) ret = -1;
  printf("%lld\n", ret);
}